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Old 01-20-2009, 03:12 PM   #16
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furnace size?


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Originally Posted by thekctermite View Post
I don't know where you live, but unless it is somewhere warm I'm going to make a generalization that a 66,000 btu/h furnace is much too small for a 2700sqft home. There are of course a number of variables, but for comparison my 2000sqft home has a 120,000btu/h 93% unit.
Not that uncommon. Wrong mind you, but not uncommon. I think that happens when the homeowner has too much input in the choice. I am a firm believer that the HO is the one holding the checkbook and should be "part" of the decision, but they often have a "bigger is better" view.

Back in the day when I was VPin the Goodman distribution, more times then not, the burnouts that required replacement (Hvaclover/Drheat: you remember those, I am sure) were also related to oversizing. That is not to say that Goodman didn't have a HX problem, but it was not uncommon to see a 100,000 btu on 1200 sq.

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Old 01-20-2009, 03:34 PM   #17
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furnace size?


Our current oil fired hot water boiler is sized at 115k BTU for a 1640 sq ft house

I did the Manual J & included the additions I am (or have) built, sq footage will increase close to 3000 sq ft. Addition is all R19 walls & R38 ceilings (old was R7). As well as an insulated unheated attic & garage. Some of the old walls are still R7, some R13, some R15

It came out around 108k BTU for the new size of the house
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Old 01-20-2009, 04:00 PM   #18
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Originally Posted by Home Air Direct View Post
Not that uncommon. Wrong mind you, but not uncommon. I think that happens when the homeowner has too much input in the choice. I am a firm believer that the HO is the one holding the checkbook and should be "part" of the decision, but they often have a "bigger is better" view.

Back in the day when I was VPin the Goodman distribution, more times then not, the burnouts that required replacement (Hvaclover/Drheat: you remember those, I am sure) were also related to oversizing. That is not to say that Goodman didn't have a HX problem, but it was not uncommon to see a 100,000 btu on 1200 sq.

i was lucky. i dumped the line before I got burned. But I never had an install that was over sized either. Nor would I let a customer dictate what size he wanted.

I take that back...had one on a Consolidated 90%er. 1000 sq ft home customer wanted 100kbtu. I argued with him and until he said he was going to use the gas company warranty plan.

I don't know how many years later I got a call from the customers home but a gas co tech was calling ME (yeah, the fur flew). He wanted me to back up the labor on a bad heat exchanger. I told him since the HO had the monthly warranty plan with the utility how come they wouldn't do it.

Gas guy says they don't cover Ht ex. He started yelling at me saying we weren't honoring or contract with the HO.

Told gas company guy labor warranty was voided as soon as they signed with gas company.





Gas co guy did it on the side. I called the city and busted him.
No license. Boy did that feel good
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Old 01-20-2009, 04:34 PM   #19
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The stat may be short cycling on the heat anticapator or cycle rate adjustment. You may get better performance setting for a slightly longer run time. Dont go to far or you will overshoot the desired temp and have large temp swings. What type of T-stat do you have?
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Old 01-20-2009, 06:04 PM   #20
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Even the most basic HVAC calc shows 108,000 - 118,000 btu needed for your selected area. Now understand that many many factors can alter this calculation, but the fact remains that you live in pretty consistantly chilly area (lots of humidity) and you did say you had 9ft ceilings and lots of glass. Both require extra heat.

Mouse over your climate #, and then enter your sq ft and then hit calculate.

http://www.hvacopcost.com/equipsize.html

This by no means is accurate, but it will somewhat close and may help answer your size question.

Good Luck
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I live in NJ in a 2800 sq. ft, 30 year old home with 3 massive 5-pane each bow windows on the the front (north side). I have a 100 btu 95% 2stage furnace locked into 1st stage (due to high static pressure) which means I have available theorhetically 61750 BTU output. It actually may be a little less because my manifold pressures were not adjusted yet. Bottom line is it hit 8 and 9 degrees "F" last week and my home temp held the 72F temp setting. It even cycled (occaisionally went off for a few minutes).

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Old 01-20-2009, 08:26 PM   #21
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There's a lot of 3000 sq ft homes that could be heated with 80,000BTU 90% furnace, that have 120,000 BTU 90s in them.
Because someone just thought it had to have a large furnace.
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Old 01-20-2009, 08:40 PM   #22
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[quote=key1cc;216280]I live in NJ in a 2800 sq. ft, 30 year old home with 3 massive 5-pane each bow windows on the the front (north side). I have a 100 btu 95% 2stage furnace locked into 1st stage (due to high static pressure) which means I have available theorhetically 61750 BTU output. It actually may be a little less because my manifold pressures were not adjusted yet. Bottom line is it hit 8 and 9 degrees "F" last week and my home temp held the 72F temp setting. It even cycled (occaisionally went off for a few minutes).

Key1[/qu

I know you had a man J done (if memory serves me) but I put 80kbtu in homes like yours.100k Seems a little big from my experience.
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Old 01-20-2009, 08:50 PM   #23
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I know you had a man J done (if memory serves me) but I put 80kbtu in homes like yours.100k Seems a little big from my experience.
No Man J, no static test, no combustion analysis, no pressure adjustment, no temp rise, no airflow balancing, no anything the hacks.....that's why I'm on sites like this......but I digress....

Actually I thank them now for contributing to me becoming more and more a HVAC everday....

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Old 01-20-2009, 09:14 PM   #24
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No Man J, no static test, no combustion analysis, no pressure adjustment, no temp rise, no airflow balancing, no anything the hacks.....that's why I'm on sites like this......but I digress....

Actually I thank them now for contributing to me becoming more and more a HVAC everday....

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They did tell you that you have survive an a close range acetylene tank explosion to join the HVAC club didn't they?
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Old 01-20-2009, 09:36 PM   #25
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They did tell you that you have survive an a close range acetylene tank explosion to join the HVAC club didn't they?
I have not even started on the AC system yet.....waiting for the cooling season...then I'll start my flurry of inquireries on super heating, super cooling, superman, etc...

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Old 01-20-2009, 09:59 PM   #26
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Dr Heat, what would you like to know about my duct work. Also, I put a new filter in 2 days ago.
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Old 01-20-2009, 10:11 PM   #27
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my t stat is a honeywell (th2110D1009) or pro 2000 series
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Old 01-20-2009, 10:51 PM   #28
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Dang. You live in the artic or something?
Now I am scared We agree
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Old 01-20-2009, 11:00 PM   #29
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They did tell you that you have survive an a close range acetylene tank explosion to join the HVAC club didn't they?
hey I've done that burned my hands and face three years ago
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Old 01-20-2009, 11:04 PM   #30
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Dr Heat, what would you like to know about my duct work. Also, I put a new filter in 2 days ago.
as much as you can tell us

A manual d is a program for laying out duct to a specific velocity or static pressure

start at the furnace and give the trunk size and number of take offs per duct as you go try to scan in a diagram if you are able.

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